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Characterization of diesel fuels and degraded diesel fuels in the environment is a common issue nowadays. Providing definitive information for litigation regarding determination and distinguishing the origins or sources of fuel spill contamination has been a significant need among the environmental forensics community. Diesel fuels contain more complex chemicals and isomers compared to gasoline. Here, we compare the use of gas chromatography – vacuum ultraviolet spectroscopy (GC-VUV), gas chromatography – flame ionization detection (GC-FID), and comprehensive two-dimensional gas chromatography – mass spectrometry (GC × GC–MS) for diesel fuel and weathered diesel fuel analysis in fingerprinting biomarkers. GC-VUV is a relatively new technique that can rapidly acquire full absorption spectra from 120 to 240 nm. Class information about individual components is readily obtained based on reference to a library of matched spectra. Direct comparison of GC-VUV, GC-FID, and GC × GC–MS was undertaken to identify different classes of compounds and biomarkers. Using GC-VUV, numerous peaks representing minor and major components were classified into different classes by applying spectral filters and, in some cases, spectral deconvolution. Isoprenoid biomarkers, such as pristane and phytane, and their ratios with n-alkanes, C 17 and C 18 , respectively, were determined The biomarker ratio results from GC-VUV matched well with both GC-FID and GC × GC–MS. About 5%–20% difference in measured biomarker ratios were obtained for a series of commercial weathered diesel standard samples, which is good enough to allow the discrimination of different weathered diesel samples, according to prior literature. [ABSTRACT FROM AUTHOR]

Abstract: The disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC×GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non-ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC×GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC×GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination. [Copyright &y& Elsevier]

Comprehensive two-dimensional gas chromatography with isotope-dilution time-of-flight mass spectrometry (GC × GC-IDTOFMS) was used to measure polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and coplanar polychlorinated biphenyl (cPCB) concentrations in ash, sediment, vegetation, and fish samples. The GC × GC capability was achieved by using a quad jet, dual stage, thermal modulator. Zone compression of the GC peaks from modulation resulted in a significant increase of the signal intensity over classical GC-IDTOFMS. The GC × GC column set used an Rtx-Dioxin 2 phase as the first dimension (1D) and an Rtx-500 as the second dimension (2D). The chromatographic separation of the 17 PCDD/Fs and the 4 cPCBs was attained in 1D except for 2,3,7,8-TCDD and CB126 for which deconvoluted ion currents (DIC) were required to be reported separately. The Rtx-500 phase separated the bulk matrix interfering compounds from the target analytes in 2D. The instrumental limit of detection (iLODs) was 0.5 pg for 2,3,7,8-TCDD. The calibration curves showed good correlation coefficients for all the compounds investigated in the concentration range of 0.5–200 pg. GC × GC-IDTOFMS results compared favorably to those from conventional isotope-dilution one-dimensional gas chromatography-high resolution mass spectrometry (GC-IDHRMS). The comprehensive mass analysis of the TOFMS further permitted the identification of other contaminants of concern in the samples. [Copyright &y& Elsevier]